GIMP or GNU Image Manipulation Program is a free, open-source image editor and is available on multiple operating systems including Windows, OS X, and Linux. Since it is an open source software, it allows you the access the program and make changes to it as per your needs. Among features that stand out in GIMP are toggle options between single screen and multi screen view options, and the side bar setting that can be used to quickly adjust tool settings. GIMP has also recently enabled third party plugins which means that you can now add a plugin and expand what this powerful software can do.
Paint.net that started off as a straightforward replacement to Microsoft’s Paint tool has now become a widely used image editing software. The best thing about this software is its user interface – it is simple and very accessible. It has user friendly and easily recognisable icons to make it easy for new or even inexperienced users to use. While it does not have some of the advanced retouching or selection features, it makes up by enabling plugins that users can install that carries out almost anything you want it to do.
Inkscape is another open-source free to use and edit software that is available. It has all the common tools that one would need to edit and retouch photographs. It also has the Spiral tool that allows you to create all sorts of vines and swirls. The interface of this software is fairly intuitive – it has the tools on the left and additional Snap Control options on the right – but it only takes a while to get used to it.
Seashore is a free image retouching software that is available on the OS X. This is as good as GIMP (which is also available on the OS X) with the difference being that Seashore is native to the OS X and as such its interface is better and it integrates with operating system much easily. There are keyboard shortcuts for most tools on this software. If you are not a shortcut person, then all the tools are lined up across the top bar of the program.